This invention generally relates to an automatic International Morse Code generator providing a predetermined numerical message, and more particularly relates to such a device which generates a selectively actuable, progressive number.
Although the following description pertains to an apparatus for generating preselected numbers in International Morse Code, it will be appreciated that certain of the features described and claimed herein may be utilized for the generation of numbers in other codes such as ASCII, Baudot or American Morse Code. The term Morse code as used hereinafter shall refer to the International Morse Code. Frequently, a Morse code operator, either in amateur or commercial practice, desires to send a progressive number with each message transmitted. In amateur practice, many operating exercises include, as part of the message format, a progressively increasing number indicating the numerical position of the message being sent with respect to others sent by the same operator. A recent survey by applicant indicates that in over sixty activities sponsored by American and foreign amateur radio organizations over fifty of them, or eighty percent, included a number in the message format. The manual transmission of such a number is exceptionally burdensome since an experienced operator may easily exceed a thousand individual message transmissions in a twenty-four hour period. As the operator's fatigue rises over long operating periods, the possibility of transmission errors increases requiring correction and thus repeated transmissions. Certain portions of a message are generally fixed such as the operator's geographical location and Morse code generators are presently available which automatically send a predetermined fixed format in response to a single manual actuation, with the digits comprising the number being individually, manually generated. Thus, it would decrease operator fatigue and eliminate a potential source of transmission error if the operator were provided with a convenient means for generating progressively increasing numbers in response to a single manual response such as the momentary depression of an appropriate switch.
Before preceding with a detailed discussion of the illustrated embodiment, the following comments, with respect to the composition of an International Morse Code number, may provide the reader with a greater appreciation for the features of this invention. A Morse encoded number is composed of a sequence of Morse code digits sent in sequence. The number may have three significant digits. In this instance, the number one would be preceded by the code transmission of two leading zeros (001), and correspondingly the number thirty-five (035) preceded by a single transmitted zero and, of course, numbers greater than ninety-nine would start with the code transmission of a whole integer. Hereinafter, such a number is referred to as a "leading zero number". Alternatively, the number generated may commence with the first digit always being a non-zero digit with all significant zeros in the preselected number preceding the non-zero digit being deleted. That is, if the preselected number is "001" only the Morse code digit one would be transmitted, the generation of the first two significant digits of the preselected number would be deleted. Such a number generation is referred to hereinafter as a "plain number".
A digit (.phi. through 9) in Morse code is composed of the generation of a combination of unique dots and dashes. A dot being one third the time length of a dash and each of the dots and dashes comprising a selected digit being separated by a time interval equivalent to the length of a dot. That is, a dot is one bit length, a dash three bits and the separation of dots and dashes comprising a digit is one bit. Each of the digits comprising a number are separated by a time interval or inter-digit space equivalent to the time length of a dash which is three times the length of a dot. For example, the number one consists of a dot followed by four dashes, for a total bit length of seventeen. The number four consists of four dots followed by a single dash for a total bit length of eleven and the number fourteen is thirty-one bits long (17+11+3). Thus, each of the ten Morse code digits have a unique bit length introducing certain character generation problems which are not encountered in the generation of numbers in other codes such as ASCII or Baudot which have fixed bit lengths.
The digits nine (9) and zero (.phi.) are the longest of the ten International Morse Code digits. Digit nine (9) being four dashes followed by a single dot (seventeen bits) and digit zero (.phi.) being five dashes (nineteen bits). Due to the relatively long time duration required to generate these digits, it has developed as an accepted practice for operators, at their discretion, to abbreviate a zero by sending the letter "O" which is three dashes long (11 bits) and the numeral nine as the letter "N" which consists of a dash followed by a dot (5 bits). The use of an abbreviated zero (letter O) is especially encountered when the number being generated is of the leading zero type; the leading zeros being sent as the letter "O". Thus, it is particularly convenient, in connection with the generation of a number whether plain or with leading zeros, to provide the operator with a convenient means of selecting either conventional or abbreviated forms of the digits zero and nine.